Technical Field
The present invention relates to systems that create a floating cutting deck for self-propelled, riding lawn mowers.
Background of the Invention
As shown in FIGS. 9-10, riding lawn mowers 10 typically include a main frame 12, a plurality of main wheels 14 connected to the main frame 12, a motor 20 connected to the main frame 12 and configured to rotate at least some of the main wheels 14 so to move the riding lawn mower 10 forwardly and rearwardly, optionally, a seat 36 connected to the top side of the main frame 12, a steering wheel 38 connected to the main frame 12 and configured to steer at least some of the wheels 14 (e.g, the front wheels 14), and a cutting deck 16 (also called a mower deck) connected to the underside of the main frame 12. The cutting deck 16 includes one or more grass cutting blades 18 that are rotated by the motor 20. Typically, the cutting deck 16 includes several wheels 40 or a roller bar attached to the bottom of the cutting deck 16 so the cutting deck 16 rides along the lawn. Typically, these cutting deck wheels 40 are located off of the ground. Typically, the mower operator adjusts the height of the cutting deck 16 at a desired height and then proceeds to mow his/her lawn at this desired height.
Most riding lawn mowers 10 use either an electrically-powered hydraulic lift system or a manual lift handle system to raise and lower the height of the cutting deck 16 relative to the main frame 12, and thereby, adjust the height that the mower 10 cuts the lawn. Electrically-powered hydraulic lift systems are typically used in expensive lawn riding lawn mowers and use a hydraulic lift to position the height of the cutting deck 16 relative to the main frame 12. By contrast, manual lift handle systems are used in the majority of riding lawn mowers, and, as shown in FIG. 1, include a lift handle 72 that has a bottom end attached to the cutting deck 16 and a top end that includes a grip 74, a slot 26 and a plurality of teeth 11A-11I adjacent to the slot 26. The grip 74 extends above the slot 26. Typically, numerals indicating the cutting height are placed next to each tooth 11, and hash marks indicate half-intervals (e.g., 1.5, 2.5, 3.5, etc). When mowing the lawn, the user locks the handle 72 into place in one of the teeth 11A and proceeds to mow the lawn. To adjust the cutting deck 16 height, the user 1) stops mowing; 2) moves the handle 72 out of the tooth 11A; 3) moves the handle 72 into the slot 26; 4) moves the handle 72 proximally or distally along the slot length 32, depending on whether the user desires to raise or lower the cutting deck 16 height; and 5) then moves the handle 72 again into another tooth 11B-11I.
The problem with such prior art manual handle lift systems and electrically-powered hydraulic lift systems is that the cutting deck 16 is locked into place relative to the main frame 12 and the main wheels 14. Thus, as shown in FIG. 10, when the riding lawn mower 10 encounters a hill 100 or other uneven terrain that causes the terrain under the cutting deck 16 to be higher than the terrain under the main wheels 14, the cutting deck 16 scalps the lawn because the height of the cutting deck 16 is fixed relative the main wheels 14.
To attempt to address this problem, a number of prior art systems have been developed that couple the cutting deck 16 to the main frame 12 using a systems of chains. The objective of these systems is to allow the cutting deck 16 to float relative to the main frame 12. Typically, the cutting deck 16 is hung between the front and rear wheels 14 and beneath the main frame 12 by chains, links or other devices, so the cutting deck 16 is adapted to rise up when skids, wheels 40, rollers and the like attached to the cutting deck 16 underside contact the lawn surface. See, for example, U.S. Pat. Nos. 6,711,885 and 5,946,893. Generally, the intent for such deck suspension system is to avoid continuing contact with the earth surface. For example, when the mower 10 rides over an earth-surface rise which is relatively severe (that is, short in horizontal length compared to the wheel base of the mower 10 and great in height compared to the pre-set elevation of the cutting deck 16) it is intended that the deck 16 will rise or “float” upwardly, so the rotary blades 18 will not hit the earth surface. Unfortunately, these hung deck systems are often overly complex and it has been reported that, even with these systems, scalping still occurs in certain terrain. Indeed, some of these systems utilize a roller on the rear of the cutting deck 16, which is believed to be problematic because the front of the cutting deck 16 would have already started to scalp the hill 100 before the roller moves the cutting deck 16 upwardly.
Thus, there is a need for lawn mower deck systems that are less prone to scalping and are cheap to make and implement into existing riding lawn mower designs.